Optical disc systems for storage of digital content, like Blu-ray discs (BD) and in particular BD-ROM, may contain interactive graphic streams that allow for graphic compositions to generate e.g. menus or game applications. A typical example is a menu, which is defined by graphic objects that represent and can be used as buttons within a graphic composition. As an example for gaming, a graphic object is used within a graphic composition for representing a playing card that appears when dealing out. The interactive screen manipulations within the menus or gaming applications are emulated by encoding multiple graphics compositions, each representing separate screen content. This is due to the restriction of a static graphic object arrangement within the graphics compositions, which does not allow any dynamic graphic object rearrangement during a lifecycle of the composition. With today's known methods, the flexibility in appearing and disappearing of graphical objects or also their changes in position on the screen is therefore limited. This is particularly disadvantageous for interactive applications, which are often related to audio-visual (AV) content of storage media.
A typical solution for the implementation of interactive graphics is interactivity emulation. This means that interactivity is created by providing a sequence of different screen images encoded by separate graphic compositions. Every graphic composition comprehends a full screen, and therefore always a new graphic composition is decoded when a part of the screen content is changed.
Graphic compositions for multiple screens are also used as a simple solution to provide interactive game applications. So, with respect to the examples mentioned above, the appearing of a playing card or a new menu button is created by decoding another graphic composition and rendering a complete new screen in the sequence. This takes a long time before the user can see the result of his remote action. The long response time is caused by searches on the disc to find the new graphics composition item, by the re-loading of the buffers and by the time needed for decoding and rendering the new graphics into the screen. This results in sluggish applications as known e.g. from DVD applications.